Manufacture of artificial threads and filaments



.20 or precipitation baths.

Patented Mar. 15, 1927.-

UNITED STATES PATENT OFFICE.

-HENRY DREYFUS, OF LONDON, ENGLAND.

MANUNAGTURE OF ARTIFICIAL THREADS AND FILAMENTS.

in Drawing. Application filed February 25, 1924, Serial n6. 695,117, and in Great Britain March 7, 1953,

This invention relates to the manufacture of artificial silk, artificial horsehair or like threads or filaments from cellulose acetate.

The invention relates especially to the manufacture of such artificial threads or filaments by the dry or evaporative method of formation, that .isto say whereinthe solutions of or containing the cellulose acetate are extruded through fine orifices into an evaporative atmosphere of air or other gaseous medium (usually heated) in order to form filaments by evaporation of solvent from them, the filaments being usually associated into threads continuously-- with their production. The invention may also be employed in the manufacture of the threads or filaments by the wet coagulation method, i. e., whereinthe solutions are extruded through fine orifices into coagulation In my previous British specification No.

210,108 and U. 8. application 8. No. 648,350,

I have shown that with highly or relatively highly concentrated solutions of cellulose acetate, threads or filaments can be obtained having special properties, being of rounder section, and showing less glitter efi'ect. 7 1

, However,' the surprising fact .has since 39 been found that the threads so produced,

while possessing these advantageous properties, show much less covering power in the .form of-finished goods such as fabrics, which is a matter of considerable importance from 5 the point of view of the value of such 'afibre. The explanation for this may perhaps be that the density of a thread pro.- duced from a concentrated solution is ,increased, and thus gives the disadvantage 40 of lowering the covering power in a fabric,

so that it is necessary to use a considerably greater number of threads for a given surface of fabric.

' e. g. below 20%. for: instance to between 20% I substantially increased covering power. At

and 10%, or below 10%, for example to 5% or less, the covering power of the threads or filaments obtained is increased, and it is possible. in this way to obtain threads of the same time the form or configuration of. the filaments or threads produced-is, in spite of the dilution, more round, and glit-' ter is avoided. Fui'ther it has been found that as the section of the filaments is more round, their liability to become more woolly in character on' heating fora long time-in water is considerably reduced or even suppressed.

This a very important desideratum in the industry, as the value of an artificial silk or like thread is judged in particular by its covering power reckoned on a certain weight of the given textile thread as compared with others.

For the present invention I employ highly viscous cellulose acetates having viscosities ranging from 50 to 100, 150, 200 or more, reckoned on the basis of an acetone solution of the cellulose acetate containing 6 grams per 100 cc. acetone as compared at 25 C. with the viscosity of pure glycerol taken as 100, in a viscosimeter, such for example as the Engler, viscosimeter. The viscosities indic'ated in the claiming clauses hereto are to be understood as- .reckoned- 'onsuch basis. These highly viscous cellulose acetates are obtainable by the processes of my British specification No. 207562 and the .specificat1on of my corresponding U. S. application Serial'No. 633,016, which specifications al-' low, as therein stated, of producing cellulose acetates of such remarkably high viscosity properties that even solutions of much greater dilution (for exam le 50% greater dilution or more) made t erewith can be. just as viscous as much more highly con V 'centrated solutions (for example solutions For example, if the concentration of the v 45 cellulose acetate solution to be spun is raised of 50% greater concentration or more) of my previously known cellulose acetates, obtained for example by the processes of my British specifications 6463 of 1915, 14101 of 1915, 100009 or 101555, which themselves were the most viscous cellulose acetates ever 100% strength) I ,lated such, ary, reaction or of threads and an enormously increased wet strength of threads madewith them, which is the best proof that the cellulose molecule is much more preserved in them. I

The spinning solutions made with the before mentioned high viscosity cellulose acetates obtainable by the processes of my said British specification No. 207562 and U. -S. application S. No. 633,016 may be of comcentrations containing less than 20% of the cellulose acetate, and more especially. less than about 16%, and particularly concentrations of from about 10% to 5% or less. Any desired solvents may be employed in making the solutions. a

The following is one example of artificial silk spinning solutions according to the invention, it being understood that this is given only by way of illustration and can be varied considerably. The parts are by weight.

Emample.

An acetone-soluble cellulose acetate is employed made for example as follows in accordance with my British specification No. 207562 or U. S. application Serial No. 633016.

100 parts by weight of cellulose, for ex ample cotton, are introduced into a mixture of about 800 parts by weight of glacial acetic acid, 15-20% of sulphuric acid rela tively to the weight'of the cellulose reckoned on the basis of sulphuric aci of by weight of acetic anhydride, this mixture having been first cooled down to 0 0.;

the temperature is only allowed to rise gradually, cooling being continued until complete solution, the reaction being continued until a test portion shows tion product is soluble in ample about 2 to 6 hours. temperature may be allowed that the acetylato rise to about tion. The acetylation product may be isoor it may be first submitted'to a secondtreatment, for example by allowing it to stand in the acetylation solution at about ordinary temperature or with slight heating, after, if necessary, adding a small quantity of water or other agent capable of destroying any acetic anhydride remaining, the product being. isolated while soluble'in acetone.

100 parts by weight of the cellulose acedtate made as described are dissolved in 900 to 1900 parts of acetone to .form the spinh ni nigsolution.

e artificial threads or filamentsv will usually be produced according to the dry or evaporative method. The t reads or filaments produced according to the invention may ormay not be subjected to traction in the gland and about 200 to 250 parts acetone, for 'ex-' If desired, the

C. towards the end of the acetylain the known way and employed as known way to draw them out to any desired fineness of denier during filaments from solutions of cellulose acetates which cellulose acetateshave viscosities of not less than 50, reckoned as aforesaid, said spinning solutions being of concentrations between about 4% and 20%.

2. A process. for the production of cellulose acetate artificial threads and filaments, which comprises spinning said threads and filaments from solutions of cellulose acetates which cellulose acetates have viscosities of not less than 50, reckoned as aforesaid, said spinning solutions being of concentrations between about 5% and 16%.

3. A process for the production: of cellulose acetate artificial threads and filaments, which comprises spinning said threads and filaments from solutions of celluloseacetates which cellulose acetates ing from 50 to about 200, reckoned as aforesaid, said spinning solutions being of concentrations between about 4% and 20%.

4. A process for the production of cellulose acetate artificial threads and filaments, which comprises spinning said threads and filaments from solutions of cellulose acetates which cellulose acetates have viscosities ranging from 50 to about 200, reckoned as aforesaid, said spinning solutions being of concentrations between about 5% and 20%.

5. A process for the production of cellulose acetate artificial threads and filaments, which comprisesspinnin'g said threads and filaments from solutions of cellulose acetates which cellulose acetates have I viscosities ranging from 50 to about 200, reckoned as aforesaid, said spinning solutions being of concentrations between about 5% and 16%.

6. Spinning solutions for artificial threads and filaments containing cellulose acetates having viscosities not less than 50, reckoned as aforesaid,'said spinning solutions being ofvconcentrations between about 4% and 20%.

' 7. Spinning solutions for artificial threads and filaments, containing cellulose acetates having viscosities not less than 50, reckoned as aforesaid, said spinning solutions being of concentrations between. about 5% and 16%.

8. Spinning solutions for artificial threads and filaments, containing cellulose'acetates aving viscosities ranging from 50 to about 200, reckoned as aforesaid, said spinning solutions being ofconcentrations between about 4% and 20%. i

9. S inning solutions for artificial threads and fi aments, containing cellulose acetates having viscosities rangin from 50 to about- 200, reckoned as aforesai said spinning solutions being 0f concentrations between about 5% and 20% 10. Spinnin solutions for artificial threads and laments, containing cellulose acetates having viscosities ran ing from 50 to about 200, reckoned as a oresaid, said spinning solutions being of concentrations between about 5% and 16%.

11. Cellulose acetate artificial threads and filaments made from solutions between about 4% and 20% in concentration, of cellulose acetates having viscosities not less than 50 reckoned as aforesaid, said threads and filaments possessing high covering power, high mechanical strength, relatively round filament section and substantial freedom from glitter. I a

12. Cellulose acetate artificial threads and filaments made from solutions between about 5% and 16% in concentration, of cellulose acetates having viscosities between 50 and about 200 reckoned as aforesaid, said threads and filaments ossessing higl icovering power, high mec anical stren h, relativelfy round filament section and su stantial freedom from glitter. k

In testimony whereof I have hereunto subscribed my name.

HENRYDREYFU-S, 

